One thing about the clear bubble I'd read was folks were unhappy about some breaking frequently. An 'ol timer wrote in to explain to tighten it, THEN loosen it just a little bit. This would allow for the difference in materials. I've been doing as he suggested. NO breakage has occurred. The Farberware I've got has a plastic "bubble" thingie...but same information applies...I guess. Once again, give me wisdom and experience anytime!